Synthesis, crystal structure and properties of a new dinuclear manganese(III) complex: a mimic for catalase

A new dinuclear manganese (III) complex [(ac)Mn (bbml)(2)Mn(ac)]. (BF4)(2). 3.5H(2)O (Hbbml=[bis(2-benzimidazolylmethyl)amino]ethanol, Hac=acetic acid) was synthesized and characterized by several physical methods. X-ray struc ture analysis shows that the complex has a dimeric unit and the two Mn(III) atoms are bridged by the oxygen atoms of the two ligands, forming a bis ( L-alkoxo)dimanganese core. The Mn-Mn distance is 3.2103 Angstrom. Electrosp ray mass spectrometry (ES-MS) experiment shows that the complex cation may easily have lost one or two ac(-) and leave unoccupied coordination site wh ich would favor the coordination and activation of hydrogen peroxide. Furth ermore, its catalytic activity for the disproportionation of hydrogen perox ide and the effect of added heterocyclic base were also investigated. The c omplex has some similarities to manganese catalase in structure and activit y. (C) 2001 Elsevier Science BY All rights reserved.